A conventional circular saw 10, as shown in FIG. 1, includes a base member 11, a rotatable table 12, a saw unit 13, and two fences 14. The rotatable table 12 is rotatably mounted on the base member 11 and is provided for holding a workpiece for cutting. The rotatable table 12 includes a radially extending cutting groove 122. The saw unit 13 is pivotally connected to the rotatable table 12, and includes a saw blade 132 insertable into the cutting groove 122 to cut through the workpiece supported on the rotatable table 12. The two fences 14 are affixed to the base member 11 and extend along the rotatable table 12 at two sides relative to the cutting groove 122. The two fences 14 are also provided for supporting the workpiece for cutting.
In order to cut the workpiece at different angles, the operator must rotate the rotatable table 12 to different angular positions. However, as the fences 14 are affixed to the base member 11, rotating the rotatable table 12 leads to an increase in the distance between the cutting groove 122 and one of the two fences 14. Doing so also causes a decrease in the distance between the cutting groove 122 and the other fence 14. In other words, the distance between the cutting groove 122 and each of the two fences 14 cannot be maintained during rotation of the rotatable table 12. To avoid the risk of one fence 14 being positioned too closely to the cutting groove 122, and thus interfering with the saw blade 132, the mounting positions of the fences 14 must take into consideration the safety range between each fence 14 and the saw blade 132. Therefore, due to the installation limitations of the fences 14, a small workpiece may not be provided sufficient support to ensure accurate cutting.